Piston pin



Aug.4 5.51930. W. H. MANNNG 1.772.187

PIsToN PIN Filed March 25, 1929 gw/Z i5 pistons.

WILLIAM TT.

IIIAINING, 0F EONTIJLC, MECHIGADT, ASSIGOR TO GENERAL MOTORS.

CORPORATIGN, DETROLT, MCEIGAN, A CORPOF/AGN 01" DELAWARE CJSTN PIN Application filed arei 23, 19:29.

.ls may be inferred Yfrom the above titlel` this invention relates particulorl)v to iinproveinents in ineens suitable tor use in connecting the pistons of internal combustion engines, or the like, with the sti-culled smell ends oi rods employed in importing' motion to the crenlrs or" engine shafts; und it is zi. particular object oi this invention to provide pins, ordinarily including relatively hard i@ outer or bearing portions, in which e plurnlity o'l metals are so employed as to assure, at ell operating temperatures, o desired lit of the 'mentioned pins Within bearing bosses such as niej; be provided Within the mentioned The thermal conduction to which piston pins are exposed being variable, it is on object oi this invention to provide o. binietellic or other plural-metallic piston pin which is 2o selt-ndjusting in response to temperature changes such es moy result from operation ot oninterne'l combustion engine, -in `which e loosening; of pins, with constant rapid weer, hns heret fore frequently resulted from an 5 expansion of piston bosses :it :i higher rote than that o the pins extending1 therethrough 5 sind advantageous embodiments of this in vention niej; include inner parts such es socolled plugs closelyT interitting Within so outer or inajor pin parte and "formed from n or metals (such as brass or aluminum) having u higher rate or rotes of thermal expension than that o the steel or other outer cylindrical ports Within Whose ends seid 35 plugs may be inserted. The result moy-be either :i close but rotation-permitting nt between. the pin and the bearing bosses which receive the same or on ectuzil binding and non-rotative permanent connection between lo the last mentioned parts nt'all operating` tenoperetures, :is hereinafter described.

@ther ohieets o' this invention, in ywhich n. liiglicoeicient metallic insert or component muy either be permanently bonded to 6 5 :in outer end herder cylindrical mejor poi-,

tion ot the pin or mm; be separately formed sind provided "with nieans for n ivedging or other engagement ot" seid maj or portion, may liest appreciated from the olloivine 'so scription of illustrative embodiments oi soviel invention, tokenin connection with the appended claim ine.

ld 1g. l is o, vertical or longitudinal and substuntiully medizin section, with ports broken sway, throughfn. piston ond a ortion of zi connectingrod, these elements eing pivotnlly interconnected by a piston pin organization which illustrates one highly ad'vzin tngeous forni of the present invention.

Fig. 2 is o partiel elevational view, taken substantinllyos indicated by the arrow l2 of Fig. l.

Fig. 3 may be regarded :is either o partial elevational View or :i partiel plan View, of an alternative forni, with ports broken .ei-Way.

Fig. l is e transverse sectional View, teken ibstnntiellyns indicated by lthe line lof 19,13.

.Figs 5 and i5 ere respectively comparable with Figs. 3 and fl, but show o. further elter-V nntive orrn ot pin.

Fig. l is a view comparable with Fig. l or (3. but showing n. further nlterniitive.

Fig. is :i view comparable with Figure 3; and is adapted to be rend either in connection with the arrow S oit Fig. 7 or the line 8-8 of Fig. 9.

Fig. 9 is :i vievv comparable with the lefthand portion of Fig l, hut showing e, pin which nitty he ot" the general type illustrated in Fig. 8.

Fig. 10 is envien' comparable with Fig. ll, but teken somewhat :is suggested by the line lG-OQO Fig. 11, 4showing nn alternative forrin-on inWordly-diininishing or Wedge-L shziped portion being formed Seperate from in outer and mujer portion.

ligzfll is view corresponding with the right-hond central portion of Fig. l, but 'showing an embodiment of the present inand, the accompanying draw rod -12 by a pin organization comprising a main and [outer cylindrical' element 13,-this element being preferably formed-ola suitable as by reaming and/or chamfering'tc a stand-4 steel and optionally provided,'-asjb y chromium p lating in a known manner, with a hard exterior bearingsurface which is suitable for engagementI by a bushing or other bearing element 14, as provided bythe small end 15 v of the connecting rod 12. -f

The respective ends of the mentioned cylindrical portion or'element 13 may be adapted,

ard interior diameter at 16, 16 to -the reception of suitable high-coefficient inner por-- tions or elements in the form of plugs 17. In preference to giving these plugs an appreciablyv tapered form or employing any threaded or sweated or welded connection be-` tween the mentioned parts, said plugs may be merely suitably rounded or beveled or 1 chamfered at .the inner ends thereof,'as suggested at 18, and shrunk, driven or pressed to prevent relative rotation between lthev main cylindrical pin element 13, or its equivalent,l

Aor tiring-fitted into their illustrated posi.

tions,in which yperipheral anges 19, if provided near the outer'ends thereof, engage With faces 20 of the cylindrical member 13 and/or conically inclined or other portions 21 of piston bosses 22. If desired, in` order and the bosses 22, said pin may be formed i very slightly over-size and/or very slightly pedient, such as a staking of thel angev tapered and pressed or driven to place; the:

insertion of the high-coeiiicient cylindrical plugs 17 then contributes tothe secure reten- -'tion ofthe outer cylindrical element 13 in 'said bosses and serves to maintain, or even increase, the initial tight fit between the pin and bosses by expansion on rises in temperar` ture during operation; and any suitable 'eir- 20 in thev general manner suggested at 21',

21, F ig. 2, may sodeform or locally eX- pand said vflange as further to diminish risk -of relative-movement between the mentioned parts or contact thereof with the cylinder wall. The piston is preferably relieved in of the plugs 17. 'Aluminum plugs-having substantially the dimensions shown in Fig.

lvhave been found satisfactory. y In' Figs. y 3 and 4, a low-coefficient outer cylindrical element 13a is shown as bonded to an inner cylindrical element 17 having ay di'erent and ordinarily a higher coeliicient f ofexpansion, the resultant pin being shown as provided With a longitudinal kerf lor slot `Within an outer cylindrical element 13a).

24?. The-composition andv relative thickness I of each of the mentionedV concentric portions may be varied in acco'rdanc'e with the condi tions of use; but Yit should be understood that the resultant product 'may be at all-times substantially rigid, even though the relatively (Whether bonded or merely tightly inserted should cause the kerf 2lia to open, through its depth'as well as its length, at higliy temperatures. v n

In the form shown in Figs. 5 and 6, an outer and optionally discontinuous cylindrical element or portion 13b is shown as integrally ,high ezipansnon lof an internal portion 17a bonded to a continuous inner cylindrical element or portion 17h; land one of the mentioned cylindrical .elements may be formed of a suitable high-coelicient metal.- For eX- ample, the outer element being provided with one or more spiral or straight longitudinal kerfs 24h (extending partially or completely through said outer portion and optionally adapted to contribute to the distribution of a lubricant or to receive strips of an additional metal, as at 24V) the inner portion 17", of any desired thickness, may. beformed of alumi'.

num, brass, or the like. l I

Fig, 7 shows a veryv simple embodiment o f-thel present invention, in which a`main cylindrical` element or portion 13C, eXternally provided with a bearing surface, receives a longitudinally-extending strip 17c of vim.

to one or to both of the faces with which it contacts; and Fig.`8 suggeststhe use, in conl y nection With elements such as have been deganination in which (a high-coefficient strip 17?. 1f employed, being bonded to .only one ,scribed in connection with Fig. 7, of an orof the adjacent surfaces of the main pin ele ment 13d), provision is made for the use of a thermally expansible and longitudinally ad]ustable Wedge element so. disposed' as to re-expand the cylindrical elementv 13d even .after Wear upon aibearing 'or the outer element or pin proper may have rendered the expansion. of. the strip elementor elements 17 d, if left in vits original position, inadequate for the desired e'ect. `For example, the bosses 22l maybe laterally or |upwardly tapped v'as at 25d; a kerf 26 (which may bea kerf to o e of Whose walls a strip or-strips 17d are bonded) .may be provided with conical or' other surfaces 27d, opposite threaded v.opennating in a conical Wedge element 29, may be so set, as by means of a nick 30d and/or a 'head or lock nut 31d, that thermal expansion .of the Wedge 29d at elevated temperatures may assure 'a desired it of the larger pin element 13d.

Any of the pins Vshown in Figs. 3-9-in-- elusive may obviously be used either with Ior Without a plug 17 of the general char acter shown and described in connection with Figs. l and 2; any of said pins may comprise inner and outer cylindrical portions 'formed ot' metals diliering' in their rates ot thermal expansion;` and/or, it desired, a high-Coelhcient Wedge element maybe disposed longitudinally ot the pin, as suggested in Figs. lO, ll and 1Q, and provided Withsuitable means for inn'ardlY adjustingr the same.

ln figures last referred to7 to illustrate the practicability of utilizing' substantially all otl the mentioned features in a single embodiment ol' the present invention (as may be desirable only under very exceptional circumstances). a pin comprising an 'outer cylindri 'al element lll and an inner cylindrical element 1T@ of high-expansion metal is shown as receivingr a plug li"l and also a longitudinally extending' and relatively movable wedge element lTU,-ivhieh may be related thereto in the general manner suggested in Fia'. l0 and may be adjustable by means such as a. screw 25". This screw is shown as eX- tending through a threaded boss 22 and as provided with substantially flat shoulders B22-adapted to engage cooperating shoulders 33, as provided by the edges ot openings 27B. extending throuahthe strip lic.

The outer cylindric il shelllf" may be longitudinally1 lierted at 24, in the general manner suggested in the Figs. and 6, and the plugl 17e', it provided, may be staked as suggested in connection With Fig. 2 and/or additionally retained by means such as an engagement of an inwardly extending cylindrical rejection 34e, integral with the screw and) engaging' the inner end ot the plug l'l'a or interlitting vvithin a suitable openingI 35'3 in said plug. The lubricating provisions suggested at 37e are not unimportant, but they are only remotely pertinent. to this invention.

is suggested in l0, the manually adjustable features mentionedl in connection with Figi. l1 or Fig. l2 may be employed in connection #with a mere split cylindrical holloiv pin l'lf; -liut it will be obvious notl only that 4the princil'iles of this invention are applicable to produce eithei` a uniformly tight lit or uniform or varying' clearance tor a desired lubricating or other eilect; and that various features of ,the present invention might be independently employed but also that numerous modilications and/or combinations additional to or quite distinct from any suggested herein might be easily devised to provide thermally seit-adapting piston pins suitable for use at abnormally high and/or ordinary and/or abnormally low operating;n temperatures, all within the scope of the present invention.

l' claim l. For use Within an engine piston, a rodconneclingj element in the Vform oiE a ther.v malty Ael t-adapting ivrist pin comprising'. an mtn'ardly disposed major portion formed of ,ier

tive lit ot said pin, Within bosses provided' upon said piston. at all operating temperaturcs of said engine.

Q. For use within an engine piston, a rod- `connecting' element in the form ol a thermall)A self-adaptingr wrist pin romprising: an outwardly disposed major portion formed of a relative hard metal providing a connecting' rod bearing' and having' a comparatively low coefficient ot' thermal expansion; and a relatively hiffh-coetlicient additional portion, so disposed therein as to maintain a non-rotative lit oif said pin, Within bosses provided upon said piston. at all operating temperatures of said engine-said major portion beine' suhstaiitially cylindrical throughout its length and said additional portion beinglr in the lorm et an end plug interlitting Within said major portion.

Il. For use Within an engine piston, a rodeonnectiuff element in the form of a thermally selt-adaptinn' Wrist pin comprising: an outwardly disposed major 'portion formed of' a relative hard metal providing a connectin irod bearing and having a comparatively low coefficient ot' thermal expansion; and a relatively high-coefficient additional portion, so disposed therein as to maintain a non-rotativeiit of said pin, Within bosses provided upon said piston, at all operating temperatures of said engine,-said major portion heing substantially cylindrical throughout'its length and said additional portion beingr in the form of an end plug interfitting Within said major portion, and having an opening extending therethrough.

4. For use within an engine piston. a rodconnecting' element in the form of a therinally self-adapting;r Wrist pin comprising: an outwardly disposed major portion formed oi* a. rglative hard metal providingT a connecting rod bearing and havingA a comparatively low coei'hcient of thermal expansion; and a relatively l'iigh-coetficient additional portion, so disposed therein as to maintain a non-rotative iit ot said pin, Within bosses provided upon said'piston, at all operatingf temperatures ot said'engine. said major portion being7 substantially cylindrical in torni and provided with a longitudinalhert.`

For use ivithin an engine piston, a rodconnecting element in the form of a thermally vself-adapting' Wrist pin comprising. an outwardly disposed major portion formed ot a relative hard. metal having a comparatively loiv coeliieient ot thermal expansion; and an additional portion termed of a relatively high coeliicient metal, so disposed ihr-rein as te assure a satisfactory lit of said nin, within bosses provided upon 'said piston,

ioo

vat substantially all operating temperatures,

of said engine, lsaid major portion being substantially cylindrical iii form and provided with a longitudinal lrerf receiving a portion of saidhigh-coetticient metal.

6. For use within an engine piston, a rod-V Connecting element in the form of a thermally'sel-adap'ting wrist pin comprising: an outwardly disposed major portion formed of a relative/ hard metal. having a comparatively low `coefficient of thermal expansion;

and a relatively high-coeilicien'tl additional .poi-tion, so disposed therein as to assure a satisfactory -litof said pin, within bosses provided upon' said piston, at substantially all operating temperatures of said engine, said,

major portion being substantially cylindrical in form and provided with a longitudinal y kerf having a wedge set therein.

7. For use `within an engine piston, a rodj connecting element in thQ-orm of a thermally self-adapting wrist pin comprising:

y an outwardly disposed major portion formed' of arelative hard-metal having a comparatively l`ow coeliicient of thermal expansion; and a relatively high-coeliicient additional portion, so disposed therein as toassure a satisfactory fit lof said pin,A within bosses provided upon said piston, 'at substantially all ,operating temperatures of said engine,

' said major portion being substantially cylin- 'wear-receiving outer drical in form and providedvlwith a longitudinal kert1 having a wedge vset therein; and means for inwardly adjusting said wedge..

8. For use in a pivotal connection`of lthegeneral character described, a self-adapting :pin comprising: asubstantially cylindrical portion having a com-v paratively low rate of thermalexpansion with its ends anchored with piston bosses; and means therein tending to eli'ect an expansion of said boss engagin ends on rise in temperatures, at a rate di erent from that of said bosses, said means comprising end plugs tightlytitting within said outer portion and formed of a'm'et-al diifering therefrom in its coecient of expansion.

-outer portion beingprovided with a longi f tudinal slot containing said means.'

10.` For use in apivotal connection of the general character described, a seliadaptingl pin comprising: a substantially cylindrical wear-'receiving outer portion having a comparatively low rate ofthermal expansion; and means therein for effecting an expansion thereof, on rise in temperatures, ata rate different from that of saidl outer portion, said,

means including a strip `of high-coeicient metal -movable within a slot in said outer cylindrical portion.

11. For use in a pivotal Iconnection of the general characterdescribed, a self-adapting' pin comprising: a substantially cylindrical wefar-receiving outer portion having a com-l paratively low rate of thermal expansion; I

and means therein for effecting an expansion thereof, on rise in temperatures, at a rate dif- -erent from that ofsaid outer portion, said lmeans including a strip of high-coeiiicient metal movable within a slot infsaid outer cylindricalportion and provided with means for its adjustment therein.

12. An anchoring means non-rotative fit between a hollow wrist pin and a piston boss during all changes in opy v for maintaining a erating temperature which consists of an elel i ment fitted within said wrist pin having a f higher coefficient ofthermal expansion than said-wrist pin and piston boss.

13. ln' awrist pinassembly, piston bosses,`

a wristpin having a comparatively low coefficient of thermal expansion press-fitted within said piston bosses, 4and means within f 'said wrist pin having a relatively highercoefficient of thermalexpansion, which is adapted to prevent any reduction in press lit aris- 4 ing between said bosses and wrist pin on a rise in operating temperature by causing expansion of said' wrist pin at a higher rateY than the expansion of said bosses. l.

14. In a wrist pin asseinblypistoii bosses,

a hollow steel* wrist pin' press-fitted within saidbosse's, and aluminum plugspress-fitted wit-hin the ends of saidwrist pin, whereby the same is rendered thermally self-adapting in that thev press-lit between thefwristfpin '-i and bosses will be maintained lor increased during all changes in operating temperature v by the relative contraction and expansion of said plugs.l Y

15. Ina piston and connecting rod assembly, a hollow wrist pin, a connecting rodj ournalled thereon, and piston bosses' Within im'A which said wrist pin is press-fitted, said wrist i pin, connecting rod and piston bosses having .substantially the'same coeilicient of thermal.

expansion, and -plugs having a relatively higher coelicient of thermal expansion fitted! within the ends of said wrist pin, whereby suitable clearance between saidjconnecting' .rod and wrist pin andsuitable press-fit between said wrist pin and piston bosses will be maintained during changes in operating temperature. y

16. An anchoring means for maintaining a non-rotative tit between a wrist pin and a piston boss duringl changes in operating teinv perature'which consists of an element fitted within an end of said wrist pin, saidpin having at such end al circumferentially cone tinuous wall and said element having a higher ifi coeicient of thermal expansion than said wrist pinand piston boss. v

17. In a wrist pin assembly, piston bosses, a steel wrist pin having cireumferentially continuous wall portions press-tted within said bosses, and aluminum plugs press-tted within said portions, whereby said wrist pin is rendered thermally self-adapting in that 

